The invention relates to method of enrichment of road information data, and using said road information data to control a drive train of a vehicle.
Methods for using maps and databases for navigating a vehicle are commonly known. These methods using systems having access to one source of road information data such as a map or a recording from vehicles which previously have been driving the same route.
The road information data is used to control the drive train, for example, such that a better performance or an environmental friendly driving or higher comfort is achieved.
The problem with these methods is that the road information data is aging and might become out of date, for example if a stretching of a road has been changed, the previously recorded road information data is not relevant any more, whereby the drive train is controlled in a manner that probably not achieves the desired objectives. A further problem is the coverage of the road information sources. No source covers all possible routes, the smaller and the more recent constructed a road is, the higher is the probability that the road information data source does not include any data about the desired road. This is a problem especially for timber trucks, which travel long distances on common roads, but also on very small and new established roads far from the common road network.
It is desirable to overcome the above mentioned problems and thereby suggest a method that enriches road information data, such that a vehicle has as high probability as possible to access relevant road information data of an upcoming route of the vehicle.
A drive train and other systems of a vehicle are controlled by an electronic control unit (ECU), and according to the inventive method the ECU uses the road information data to control at least one parameter of the vehicle, especially a parameter of the drive train. An optimised control of the vehicle depending of the topography of an upcoming route can thereby be performed.
The ECU having access to road information data from a plurality of different types of road information sources, wherein the road information sources at least comprises a digital map, a fleet database and a local vehicle database. The ECU is adapted to make a selection between road information data from the plurality of road information sources, wherein said selection is based on a data quality rating of the road information data from the different road information sources.
The digital map is any commercial or industry generated digital map, based upon topographic data. The map would thereby at least provide for the route of a road in latitude, longitude and elevation. Such digital maps are commonly known and for example used in vehicle navigation systems.
The fleet database comprises road information data recorded by a plurality of vehicles and transmitted to and saved into the fleet database. The more vehicles that records road information data into such a fleet database, the faster the database is filled, and the fleet database thereby also becomes a greater selection of routes. The ECU must not necessary have a direct connection to the fleet database, when it has access thereto it can access relevant road information data and store it in a local memory. Obviously a wireless connection over GPRS or similar is preferable to maintain a high flexibility in the system.
The local vehicle database just comprises road information data that has been recorded by the vehicle itself.
The road information data in the road information data sources is tagged with a quality rating. The quality rating reflects the relevance of the road information data and facilitates an evaluation of the road information data from the different road information data sources, such as a selection there between can be made.
The ECU further has access to a vehicle position sensor, wherein the vehicle position sensor can be any kind of positioning device, enabling a vehicle positioning, for example a satellite based navigation system or an inertial navigation system or any other suitable positioning determining device.
The position sensor can also be complemented by a navigation system, which can be any kind of navigation system enabling a planning of an upcoming route. Said navigation system can be of a black box type, just used for the control of the vehicle or it can also be used by and used to inform an operator of the vehicle.
The inventive method comprising the steps of                determining a position of the vehicle,        collecting road information data, about possible routes in surroundings of the position of vehicle, from the plurality of road information sources (A, B, C),        evaluating the data quality rating of the collected road information data,        selecting the mad information data with the highest data quality rating, and        controlling at least one parameter in the drive train dependent of the selected road information data,        registering, road information data about the route as the vehicle is moving, and during move of the vehicle, performing, the steps of;        making a selection of relevant recorded road information data, and        saving said relevant road information data to the local database (C).        
The position of the vehicle is determined with the earlier described position sensor. The same sensor is used by the ECU to register the position of the vehicle when the vehicle is moving. Further, information of an inclination of the road is also registered. For this purpose, an inclination sensor in a transmission of the vehicle or any other means to detect an elevation can be used. A selection of relevant registered road information data is made, to filter out incomplete or otherwise defect registered data. The selected data is then saved into the local database, from which it can be accessed by the ECU during the next drive along the same route.
The inventive method has the advantage that the ECU can choose from a plurality of road information data sources, and use the one with the highest quality. Especially, the road information data the ECU can access is enhanced, because the traveled route of the vehicle is recorded and saved into the local database, such that always fresh road information data is accessible. If neither of the accessible road information sources comprises any relevant road information data, the drive train cannot be controlled dependent on any road information data. However, since the traveled route is recorded and saved in the local database, the ECU will have access to road information data, next time the vehicle travels the same route. The inventive method is preferably repeated continuously.
It is preferred that the position sensor, does not only decide the position of the vehicle, but also determines a direction of travel of the vehicle. By using the information about the direction of travel of the vehicle, the ECU must not collect road information data about all the routes in the surrounding, instead just the routes in the direction of travel is collected.
In the inventive method the road information data is tagged with a quality rating. The quality rating enables an evaluation of the road data from the different road information data sources, whereby a selection of the road data with the highest quality rating, can be made. The quality rating is based on different criteria, wherein these criteria at least comprises one of following                the source of the road information data and/or        the age of the road information data, and/or        the amount of records a mean value of the road information data is based upon, and/or        the spread of a mean value of the road information data and/or        the deviation between an expected outcome of the control of the at least one vehicle parameter and an actual outcome of the control of the at least one vehicle parameter.        
The road information data from the different road information sources have different priority order; the priority order is decided by the quality rating. Road information data with higher quality rating has precedence before road information data with a lower quality rating.
To enable a rating based on the age of the road information data, is the road information data saved in the local database, together with its correspondent date of recording.
The different criteria can be weighted, such that one or some of the criterions has/have a higher influence of the final quality rating. This allows a selection of the road information data with the highest quality, i.e. comprises the most relevant information about the upcoming route.
Not all pans of a road involve such topographic that a planning of the driveline strategy is required to achieve optimal values for performance and/or comfort and/or environmental friendly driving. Therefore it is suggested that the road information data for a route is saved in portions. Whereby just those portions where a change in inclination and/or the direction of the road fulfil predefined conditions in change of inclination and/or direction are saved in the local database. Thereby it is not necessary to occupy physical and digital storage space with irrelevant information and the internal database can be made smaller, whereby costs are saved.
The second time the same road or portion of a road is saved into the local database, a mean value of first and second road information data is created. This procedure is repeated each time the same route or portion of a route is recorded and saved into the local database. Hence, if the local database includes several recordings of the same route, a mean value of that route is formed from said several recordings. Using a mean value instead of just one recording assures more relevant road information data, because the mean value reduces the influence of variations in the recordings, such as outer circumstances and problems with sensors during a specific recording.
When calculating a mean value it is possible to weigh the most recent recording higher than an older recording, whereby the recent recording becomes a higher relevance in the mean value.
In the data quality rating the quality of a mean value can be rated, whereby a mean value with a low spread between the individual recordings becomes a higher data quality rating than a mean value with a higher spread between
the individual recordings. This can be applied for mean values in the local database as well for mean values origin from the fleet database.
The different criteria for the road information data can be used individually or combined in any combination with one or several other criteria to create a final value of the data quality rating.
To assure that relevance of the mean value, such that it does not get contaminated with erroneous recordings, a comparison between the current mean value and newly recorded road information data is made before the newly recorded data is integrated into the mean value. Whereby, if the most recent recording of a route differs more than a predefined percentage from a mean value of the road information data for said route, said new recording is not included in the mean value, wherein said most recent recording is saved separately.
However, if the route actually has changed the mean value obviously must be updated. A change of the route is thereby certified in that, if both the most recent and the predetermined number of earlier recordings of a route differs more than a predefined percentage and about equally much from the mean value, a new mean value is calculated from the most recent and the number of earlier recordings of said route. Whereby the previous mean value can be discarded.
To enhance also the date in the fleet database, saved road information data is transferred into existing road information data about the route of interest, in the local database. This transfer of data can be made continuously or when the vehicle arrives at a transit station or during service or at an other suitable moment and location. Whereby the data transfer can be made wirelessly or by cable with suitable means therefore.
A mean value from a high number of recordings is seen as more reliable as a mean value with a lower number of recordings. Thereby, in the data quality rating, a mean value from a higher number of recordings becomes a higher data quality rating than a mean value based upon a lower number of recordings.
To eliminate erroneous recordings, the outer conditions during driving of the vehicle are taken into consideration in the recording. Such outer conditions can be wind, snow, rain and traffic conditions.
The inventive method allows the ECU to control the drive line of the vehicle such that it performs optimal according to predefined criterions. These criterions can be optimal performance regarding comfort, power, eco driving etc. Thereby can the engine control strategy and/or the gear shift strategy of an automatic transmission of the drive train be a function of the topographic of the upcoming route. Such a control of the drive train is preferably implemented during an activation of a cruise control of the vehicle, whereby the method thereby comprises the steps of changing the set speed of the cruise control dependent of the selected road information data.